When and how to use form methods - django

Question

I am reading the Django documentation and ran across a couple examples in the forms sections that I do not understand why they did something 2 separate ways..
In the first example I found they send email from the FBV. This makes a lot of sense to a beginner:
from django.core.mail import send_mail
if form.is_valid():
subject = form.cleaned_data['subject']
message = form.cleaned_data['message']
sender = form.cleaned_data['sender']
cc_myself = form.cleaned_data['cc_myself']
recipients = ['info#example.com']
if cc_myself:
recipients.append(sender)
send_mail(subject, message, sender, recipients)
return HttpResponseRedirect('/thanks/')
In the second example I found they use CBVs and apply methods to the form and call this method in the view:
from django import forms
class ContactForm(forms.Form):
name = forms.CharField()
message = forms.CharField(widget=forms.Textarea)
def send_email(self):
# send email using the self.cleaned_data dictionary
pass
from myapp.forms import ContactForm
from django.views.generic.edit import FormView
class ContactView(FormView):
template_name = 'contact.html'
form_class = ContactForm
success_url = '/thanks/'
def form_valid(self, form):
# This method is called when valid form data has been POSTed.
# It should return an HttpResponse.
form.send_email()
return super().form_valid(form)
When should you apply form methods and call those methods in the view? Is there a benefit to writing the code this way?
Also, in the second example they used pass in the send_email() method. I wanted to investigate further so I applied this to simple invite form I had..
class InviteForm(forms.Form):
name = forms.CharField()
phone = PhoneNumberField(help_text='Format must be: [phone]', required=False)
email = forms.EmailField()
subject = forms.CharField()
message = forms.CharField(widget=forms.Textarea)
def send_email(self):
send_mail(self.subject, self.message, 'someone#company.com', [self.email])
class InviteView(FormView):
template_name = 'invite/invite_form.html'
form_class = InviteForm
success_url = reverse_lazy('overview')
def form_valid(self, form):
form.send_email()
return super().form_valid(form)
Issue here is that I get:
AttributeError at /invite/
'InviteForm' object has no attribute 'subject'
Do I have to create parameters and pass them as arguments in the view after pulling the forms cleaned_data? If so, what is the point of creating the form method?

Answer 1

There isn't really a "correct" way of doing this. One could argue for doing this in the view but there are also good arguments to be made why send_mail should be part of the form.
Personally I like to keep my views as concise as possible. This is the first thing you read when you try to understand the behavior of the app. By just writing form.send_mail() it's clear that an email will be sent based on the data passed to the form. How this is done is nicely hidden and not really of concern to the view.
If you then later want to change what gets sent in the email, all the functionality is in one place, the form: the fields to populate and the send_mail functionality.